This invention relates to an asynchronous transfer mode (ATM) network, particularly, relates to a method of controlling bandwidth of virtual path between two ATM subscriber switches connected to each other through at least one ATM transit switch.
An ATM network must guarantee bandwidth of a call which is established by negotiation with the terminal (i.e. a source) to guarantee quality of the call. This is because traffic of data transmitted by the terminal is changed with time and the ATM network can neither determine nor estimate the data traffic.
The ATM network negotiates with the terminal to decide a maximum data transfer rate when the call is established. The ATM network guarantees the maximum data transfer rate to guarantee perfect quality of service (QoS) for the call.
In the ATM network, each node which relates to the call must process some tasks when the call is established and released. For example, the node calculates free bandwidth and renews a management table.
There is a case that an ATM transit switch is connected to many terminals through a plurality of ATM subscriber switch. In this case, the ATM transit switch relates to the many calls and spends a long time for processing the tasks. Accordingly, the ATM transit switch will become bottleneck for the conventional ATM network.